The present invention relates to an improvement of a small hydroelectric power generator which uses hydroelectric power generated by the flow of water through a faucet.
Conventionally well-known is an automatic tap apparatus that lets water flow as a sensor senses the presence of a hand placed beneath a faucet.
The configuration of the above mentioned small hydroelectric power generator is briefly described below. In a small hydroelectric power generator, a fluid inlet path and a fluid outlet path are provided in a main case and a partition ring is located therebetween. The water entering the fluid inlet path is divided along a cylindrical wall of the ring and ejected through ejecting openings created in the cylindrical wall.
The ejected water hits on and turns a hydraulic turbine, which is rotatably arranged inside the wall, and exits from the water outlet. A rotator is fixed integrally to a rotary shaft of the hydraulic turbine. The outer circumferential surface of the rotator is magnetized in order to be a rotor magnet. A stator is opposed to the outer circumferential surface of the rotor magnet, interposing a stainless steel partition. A power generating coil is provided in the stator so that, as a magnetic flux enters the stator, the magnetic flux and the coil are inter-linked to generate power.
FIG. 8 shows an example of the configuration of a hydraulic turbine and a rotator (a magnet and a rotary shaft are not included), which are used in the above mentioned small hydroelectric power generator: FIGS. 8(A), (B) and (C) are respectively a front view, a plan view, and a bottom view thereof. In FIG. 8, the hydraulic turbine 3 comprises a rotational center portion 33 which is to be placed around and fixed to the rotary shaft, a plurality of blade members 31 which are joined to the rotational center portion 33 by inner peripheral end portions 33 thereof, and a cylindrical ring portion 32 to which outer peripheral point portions of the blade members 31 are joined. A rotator 4 is formed integrally with the hydraulic turbine.
FIG. 10 shows another example of the configuration of the hydraulic turbine and the rotator used in the above mentioned small hydroelectric power generator: FIGS. 10(A), (B) and (C) are respectively a front view, a plan view, and a bottom view thereof. The hydraulic turbine 3 comprises the rotational center portion 33 which is placed around and fixed to the rotary shaft, and a plurality of blade members 31 which are joined to the rotational center portion 33 by the inner peripheral point portions thereof. The hydraulic turbine 3 in FIG. 10 is configured without the ring portion 32 which is present in FIG. 8.
However, in the above mentioned small hydroelectric power generator, when the flow of the water passing through the fluid path increases, the following problem occurs: when the hydraulic turbine 3 rotates as the water passes by, the outer peripheral point portions of the blade members 31 temporarily block a portion of ejecting openings 22; therefore, the hydraulic pressure is inconstantly applied onto the blade members 31.
In other words, each of the blade members 31 of the hydraulic turbine 3 of FIG. 10 is configured such that the width, d1, of the outer peripheral point portion in the plan view and the width, d2, of the outer peripheral point portion in the bottom view are respectively set to about 1 mm. For this reason, as illustrated in FIG. 11 containing a sectionally enlarged view, the ejecting openings 22 (The wider the width is, the more the fluid flows; however, the hydraulic pressure is decreased with the wider width and accordingly the power generating capability is reduced. So in this embodiment, the width, d3, is set to about 1.5 mm to obtain an appropriate power generating capability.) for ejecting water inside the water dividing ring-shaped wall portion 2, which is located between the water inlet path12 and the water outlet path13 and in which the hydraulic turbine 3 is provided, are partially blocked by the outer peripheral point portions of the blade members 31 when the hydraulic turbine 3 is turned. Consequently, the hydraulic pressure becomes inconstant and the rotation of the hydraulic turbine 3 becomes imbalanced, causing vibrations to the entire tap. Thus, this increases the rotation noise as well as the vibration noise.
The above mentioned problem occurs with the hydraulic turbine and the rotator of both FIG. 8 and FIG. 10. FIG. 9 is a graph of flow rate (liter/min) versus noise (decibel) when the hydraulic turbine and the rotator of FIG. 8 are used. The noise above 35 decibel occurs at a flow rate of about 6.0 liter/min.
In the same manner, FIG. 12 is a graph of the flow rate (liter/min) versus the noise (decibel) when the hydraulic turbine and the rotator of FIG. 10 are used. In the graph, A, B, and C are samples of the hydraulic turbine and the rotator of the same configuration. With each sample, the noise exceeding 35 decibel occurs at a flow rate of about 6.0 liter/min.
As described above, when the sound generated in the small hydroelectric power generator exceeds 35 decibel at a flow rate of about 6.0 liter/min, it becomes a harsh noise to the ear of the user using the automatic tap apparatus.
Thus, the objective of the present invention is to provide a small hydroelectric power generator in which the noise generation is reduced by improving the configuration of the hydraulic turbine.
To achieve the above objective, the present invention provides a small hydroelectric power generator having a main case equipped with a fluid path, a hydraulic turbine arranged in the fluid path and turned as a fluid of a predetermined flow passes by, a rotator connected to the hydraulic turbine to rotate together with the hydraulic turbine, the rotator acting as a rotor portion opposed to a stator portion, so that power is generated by rotating the rotor portion relative to the stator portion as the fluid passes by; wherein a plurality of ejecting openings are provided in the fluid path outside the rotational path of the hydraulic turbine for reducing an area of a flow of the fluid and then for ejecting the fluid; and the hydraulic turbine has a rotational center portion and blade members onto which the fluid ejected from the ejecting openings hits, each of the blade members being formed such that the inner peripheral end portion is joined with the rotational center portion and outer peripheral point portion is extended near the ejecting openings and formed in an edge-shape.
With this, the ejecting openings will not be blocked by the point portions of the blade members of the hydraulic turbine. Therefore, a constant hydraulic pressure is provided. Also, since the water is constantly ejected from the ejecting openings at a plurality of locations, the hydraulic turbine rotates smoothly, thus reducing the rotation noise. Further, the hydraulic pressure and the current are kept constant, and accordingly the vibration noise of the case and the current noise will be reduced.
According to another aspect of the invention, in the above small hydroelectric generator, the width of the portion, which is the point portion of the blade member and formed in edge, in the circumferential direction is set to 30% or less of the width of the ejecting opening in the rotational direction of the hydraulic turbine. For this reason, the ejecting openings are blocked less by the point portions of the blade members of the hydraulic turbine, compared to the one in a conventional configuration. Thus, vibrations and rotation noise which are normally caused by the change in the hydraulic pressure can be reduced.
Also, according to another aspect of the present invention, in each of the above small hydroelectric generator, the plane of the blade member, the side opposite from the plane which receives the fluid, is curved from the inner peripheral end portion to the outer peripheral point portion with the center portion projected. Since the curved planes are the front planes during the rotation, and the blade members can rotate receiving less resistance from the water. Therefore, the hydraulic turbine rotates smoothly. Accordingly, the rotational vibration and noise can be further reduced.
Further, according to another aspect of the present invention, in each of the above small hydroelectric generator, the rotational center portion of the blade member is formed in a shaft shape extending to be perpendicular to the direction in which the fluid is ejected from the ejecting openings, and rotating wings are provided extending from the outer peripheral point portions in the circumferential direction to be parallel to the rotational center portion formed in the shaft-shape so that the ejecting openings are not blocked. Therefore, the ejecting openings will not be blocked, increasing the rotation force of the hydraulic turbine.